56 
EDITORIAL OBSERVATIONS. 
escape. No one who has carefully watched the course of 
pleuro-pneumonia of cattle, can assert that this account 
is explicitly true of it ; on the contrary, it is impos- 
sible to predicate of an outbreak when the malady will 
cease, or how many victims it will seize, what time will 
elapse between the attacks, or after what period the re- 
mainder of the herd may be considered safe. Sometimes 
one animal after another is taken ill at an interval of a 
fortnight, and then several may be smitten almost on the 
same day. This kind of thing often goes on pretty 
regularly in some parts of the country, but in. others, 
where the circumstances are totally different, the disease 
will assume a much more irregular character. Perhaps one 
animal is attacked and dies, and the disease is at an end ; 
or in another instance, cases occur at various periods for a 
long time, and then disappear entirely. Change in the 
system of feeding and general management has, in our 
experience, been frequently followed by the sudden cessa- 
tion of the disease after a considerable period of its 
continuance in a malignant form. 
In the light of these facts, relating to the progress of the 
disease, we may proceed to consider some of those re- 
ferring to the results of inoculation. That the introduc- 
tion of a few drops of serum from the luugs of a diseased 
ox causes pleuro-pneumonia, or any disease bearing the 
slightest resemblance to it, no one believes or asserts. 
Therefore, whatever influence the operation may have can- 
not be due to the induction of the condition which usually 
attends inoculation with the matter of other contagious 
disease. 
The local effects of swelling and suppuration may be pro- 
duced over and over again in the same animal, and in this 
particular the introduction of the serous exudation differs 
entirely from inoculation with the matter of other contagious 
diseases. 
Inoculated, animals are in many instances subsequently 
attacked with pleuro-pneumonia. As a matter of fact cows 
have died of the disease after having lost their tails from 
the effects of the inoculation. This again is contrary to 
the experience of inoculation with the matter of other con- 
